The present invention is directed to electronic circuitry and in particular to cooling it.
The operation of certain types of electronic circuitry, particularly circuits of the type intended to operate at very high speeds, depends to an extent on the positioning of circuit components on the circuit boards in which the circuitry is embodied. It thus is often desirable to be able to position the components in such a way as to maximize, say, the speed of which the circuit is capable. But the positions that would be most desirable from a speed standpoint sometimes cannot be adopted in practice, because to do so would make it difficult to cool the circuitry properly by ordinary fan cooling.
To reduce such component-positioning constraints, it has been proposed to use a cooling arrangement of the type described, for instance, in U.S. Pat. No. 4,498,118 to Bell, in which a generally planar cooling module, more or less in the shape of a circuit board, is disposed to face the circuit board's component surface. The cooling module has an internal plenum that forms openings opposite individual, targeted components on the circuit board, and air flowing through the plenum is thereby directed preferentially to the components most in need of cooling. Air directed to a given component thus is not subjected to heating by "upstream" components, and the circuit designer is thus afforded greater freedom in component positioning.
This approach has not been widely adopted, though, presumably because such a plenum adds considerable weight and some cost to the circuit assembly.